In recent years, there has been a focus on fuel cells for generating electricity using an electrochemical reaction of hydrogen and oxygen as an energy source. Water is generated by the electrochemical reaction from fuel cells. The generated water has been used for cooling of the fuel cell system interior, and is discharged from a water discharge pipe to the outside.
When this kind of fuel cell system is stopped for a fixed time under low temperature conditions, such as when the outside air temperature is lower then the freezing point, the water collected in parts inside the system, such as a gas-liquid separator, freezes. This causes water to be discharged from the water discharge pipe to the outside impossible, which generates gas accumulation, so that the fuel cell system cannot operate, and there is the risk of shortening life of the fuel cell system.